ELECTROLYSER TECHNOLOGIES · PEMWE
Follow the journey through a PEM cell
Water in. Protons through the membrane. Electrons around it. Hydrogen out.
Look for the glowing outline
Cell components and reaction reference
Anode: H₂O → ½O₂ + 2H⁺ + 2e⁻
Cathode: 2H⁺ + 2e⁻ → H₂
Overall: H₂O → H₂ + ½O₂
Cathode: 2H⁺ + 2e⁻ → H₂
Overall: H₂O → H₂ + ½O₂
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Symbols and cell parts
- PEM
- Proton exchange membrane: a hydrated polymer electrolyte that conducts H⁺ between the electrodes.
- H⁺
- A proton, shown as the mobile ionic charge carrier. It moves from anode to cathode.
- PTL
- Porous transport layer: carries fluids and electronic current, and supports the catalyst layer.
- CL
- Catalyst layer: the thin reaction region containing catalyst at an electrode.
- BPP / flow field
- Bipolar plate / fluid-distribution channels: conduct current, distribute fluids and support the cell.
- Anode (+)
- The positive electrode during electrolysis; oxidation releases electrons here.
- Cathode (−)
- The negative electrode during electrolysis; reduction consumes electrons here.
- DC power supply
- A direct-current source that supplies electrical energy and maintains the electrode potential difference.
- e⁻
- An electron. Electronic charge travels through conductive components and external wires.
- H₂O
- Water; H₂O(g) means water vapour (steam).
- H₂ / O₂
- Hydrogen gas / oxygen gas. Subscript ₂ means two atoms per molecule.
- OER / HER
- Oxygen evolution reaction / hydrogen evolution reaction.
- Oxidation / reduction
- Loss of electrons / gain of electrons.
- Reaction notation
- → means “forms”; + joins reactants or products. A coefficient such as 2 or ½ gives the relative number of molecules or moles.